Combustion burner

ABSTRACT

A combustion burner  10 A according to one embodiment of the present invention includes: a fuel nozzle  110 ; a burner tube  120  forming the air passage  111  between the burner tube  120  and the fuel nozzle  110 ; swirler vanes (swirler vanes)  130  arranged in a plurality of positions in the circumferential direction on the external circumferential surface of the fuel nozzle  110 , each extending along the axial direction of the fuel nozzle  110 , and gradually curving from upstream toward downstream; and a liquid fuel injecting hole  133 A from which a liquid fuel is injected to a surface of each of the swirler vanes  130 . The combustion burner  10 A also includes multi-purpose injecting holes  11 - 1  to  11 - 3  as a cooling unit that cools a part of a vane pressure surface  132   a  of the swirler vane  130  on which the liquid fuel LF hits. Water is injected through the multi-purpose injecting holes  11 - 1  to  11 - 3  to form a water film  15 A on the vane pressure surface  132   a , whereby a combustion temperature is reduced and formation of carbon deposit is prevented.

TECHNICAL FIELD

The present invention relates to a combustion burner that uses eitheronly a liquid fuel, or both of a liquid fuel and a gas fuel, as a fuel.

BACKGROUND ART

A gas turbine, such as one used for generating power, includes, as itsmain components, a compressor, a combustor, and a turbine. Many gasturbines have a plurality of combustors, and the combustors included inthe gas turbine are arranged in a circle in a combustor casing. Aircompressed by the compressor is mixed with fuel supplied into thecombustors, and is combusted. Such combustion takes place in each of thecombustors to generate high temperature combustion gas. The combustiongas, produced by the combustion, is supplied to the turbine to drive theturbine in rotation.

FIG. 8 indicates an exemplary structure of a combustion burner includedin a combustor of a conventional gas turbine. As shown in FIG. 8, thiscombustion burner 100A is arranged in plurality (in FIG. 8, only one isdepicted), surrounding a pilot combustion burner 200. A pilot combustionnozzle, not shown, is installed in the pilot combustion burner 200. Thecombustion burner 100A and the pilot combustion burner 200 are arrangedin a combustion liner of the gas turbine. The combustion burner 100Aincludes, as main component thereof, a fuel nozzle 110, a burner tube120, and swirler vanes (swirler vane) 130 (Patent Documents 1 and 2).

The burner tube 120 is arranged along the same axis as the fuel nozzle110, surrounding the fuel nozzle 110, to provide a ring-like air passage111 between the external circumferential surface of the fuel nozzle 110and the inner circumferential surface of the burner tube 120. Compressedair A flows through the air passage 111 from upstream (from theleft-hand side in FIG. 8) to downstream of the air passage 111 (towardthe right-hand side in FIG. 8). The swirler vanes 130 are arranged in aplurality of positions along the circumferential direction of the fuelnozzle 110, each extending in the axial direction of the fuel nozzle110. A clearance (gap) 121 is kept between the tip (tip) of the externalcircumference of each of the swirler vanes 130 and the innercircumferential surface of the burner tube 120, generating a leaking airflow that flows around a vane pressure surface of each of the swirlervanes 130 to a vane suction surface thereof. This leaking flowinterferes with the compressed air A to generate a vortical air flow. Byway of such a vortical air flow, the compressed air A is effectivelymixed with vaporized and atomized fuel F injected from a point near thetip of the fuel nozzle 110 to the vane surface. In this manner, evendistribution of the fuel is promoted. The reference numeral 131 in FIG.8 indicates a clearance setting rib.

The gas turbine uses not only a gas fuel but also a liquid fuel as afuel. Conventionally, when a liquid fuel is used, the liquid fuel isinjected through a liquid fuel injecting hole toward the flow of thecompressed air. In this manner, the injected liquid fuel is sheared bythe compressed air flow, and becomes atomized and mixed with air. Theliquid fuel that is atomized and mixed with air is then combusted.

Examples of liquid fuels include, the bunker A, light oil, and dimethylether that are so-called oil fuel.

When a liquid fuel is used in the conventional combustion burner 100A,the liquid fuel is supplied from the point near the tip of the fuelnozzle 110, and each of the swirler vanes 130 gives a swirling force tothe compressed air A that is flowing through the air passage 111 toobtain a swirling air flow a. The kinetic momentum of the swirler air isused to atomize the liquid fuel, and to reduce NO_(x) and suppress soot.

However, the conventional combustion burner 100A, such as the one shownin FIG. 8, has been limited in its capability to atomize the liquidfuel. Furthermore, it has been extremely difficult to make the fueldensity uniform in the fuel nozzle 110.

To prevent these problems, a combustion burner has been suggested topromote atomization and to make the fuel density uniform. FIG. 9 is aschematic of an exemplary structure of another conventional combustionburner. FIG. 10 is a perspective view of the fuel nozzle included in theconventional combustion burner. As shown in FIGS. 9 and 10, thisconventional combustion burner 100B supplies a liquid fuel LF throughliquid fuel injecting holes 133A arranged on the surface of the fuelnozzle 110. The liquid fuel LF, injected through the liquid fuelinjecting holes 133A, is injected toward the vane pressure surface 132 aof the swirler vane 130. On the vane pressure surface 132 a, the liquidfuel LF spreads out into a thin film. The liquid fuel LF that is spreadinto a thin film is sheared by a high-speed air flow, to become atomizedand vaporized. In this manner, atomization is promoted, and uniform fueldensity is achieved (Patent Document 3).

[Patent Document 1] Japanese Patent Application Laid-open No. H11-14055

[Patent Document 2] Japanese Patent Application Laid-open No. 2004-12039

[Patent Document 3] Japanese Patent Application Laid-open No.2006-336997

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

However, in the combustion burner 100B, the temperature of thecompressed air A becomes relatively high, e.g., approximately 450Celsius degrees, while using the liquid fuel LF. If the vane pressuresurface 132 a of the swirler vane 130 heated to high temperature by thecompressed air. A is brought in contact with the liquid fuel LF, carbondeposit can be produced.

In consideration of the problems above, an object of the presentinvention is to provide a combustion burner that can suppress formationof carbon deposit on a part of a swirler vane surface on which a liquidfuel hits.

Means for Solving Problem

According to an aspect of the present invention, a combustion burnerincludes: a fuel nozzle; a burner tube that surrounds the fuel nozzle toform an air passage between the burner tube and the fuel nozzle; aplurality of swirler vanes being arranged in a plurality of positions ina circumferential direction on an external circumferential surface ofthe fuel nozzle, each of which extends along an axial direction of thefuel nozzle, and gradually curves from upstream to downstream so as toswirl air flowing in the air passage from the upstream to thedownstream; a liquid fuel injecting hole that is formed on the fuelnozzle, and from which a liquid fuel is injected to a vane surface ofeach of the swirler vanes; and a cooling unit that cools a part of thevane surface on which the liquid fuel hits.

Advantageously, in the combustion burner, the cooling unit includes amulti-purpose injecting hole that is arranged on a vane pressure surfaceof each of the swirler vanes, and from which a gas fuel is injectedduring gas combustion, and water is injected to the vane pressuresurface of the swirler vane during combustion of the liquid fuel.

Advantageously, in the combustion burner, the cooling unit includes awater injecting hole that is arranged upstream of the liquid fuelinjecting hole provided on the fuel nozzle, and in line therewith, andfrom which water is injected to the vane pressure surface of the swirlervane.

Advantageously, in the combustion burner, the cooling unit injects amixed fuel prepared by mixing water and the liquid fuel evenly from theliquid fuel injecting hole to the vane pressure surface of the swirlervane.

Advantageously, in the combustion burner, the cooling unit includes awater cooling circuit formed inside the swirler vane.

Advantageously, in the combustion burner, the liquid fuel injecting holeis arranged on a vane pressure surface of the swirler vane, and thecooling unit includes a water injecting hole that is arranged upstreamof the liquid fuel injecting hole on the vane pressure surface, and fromwhich water is injected to the vane pressure surface of the swirlervane.

Advantageously, in the combustion burner, the liquid fuel injects theliquid fuel to any one of the vane pressure surface and a vane suctionsurface of the swirler vane or both of them.

Effect of The Invention

According to the present invention, because the combustion burnerincludes the cooling unit that cools the part of the swirler vanesurface on which the liquid fuel hits, it is possible to prevent thepart of the swirler vane surface on which the liquid fuel hits frombeing heated up, to prevent formation of carbon deposit.

Furthermore, because the combustion burner includes, as the coolingunit, a multi-purpose injecting hole arranged on the vane pressuresurface of the swirler vane for injecting a gas fuel during gascombustion, and injecting water during'liquid fuel combustion to thevane pressure surface of the swirler vane, a water film can be formed onthe vane surface on the vane pressure surface to cool the part of thevane surface on which the liquid fuel hits. In this manner, a combustiontemperature can be reduced, and formation of carbon deposit can beprevented. Furthermore, NO_(x) in the combustion field can also bereduced.

Furthermore, because the combustion burner includes, as the coolingunit, the water injecting hole that is arranged upstream of the liquidfuel injecting hole provided on the fuel nozzle and in line therewith,and from which water is injected to the vane pressure surface of theswirler vane, a water film can be formed on the vane pressure surface ofthe swirler vane to cool the part of the swirler vane surface on whichthe liquid fuel hits. In this manner, a combustion temperature can bereduced, and formation of carbon deposit can be prevented.

Furthermore; because the combustion burner includes the cooling unitthat injects mixed fuel prepared by mixing water and the liquid fuelevenly through the liquid fuel injecting hole to the vane pressuresurface of the swirler vane, the water becomes vaporized first to reducethe combustion temperature, and to deprive temperature from the surfaceof the swirler vane. Therefore, formation of carbon deposit can beprevented.

Furthermore, because the combustion burner includes, as the coolingunit, the water cooling circuit formed inside the swirler vane, thetemperature on the surface of the swirler vane can be reduced, to coolthe part of the vane surface on which the liquid fuel hits, and tosuppress the swirler vane from being heated up. In this manner,formation of carbon deposit can be prevented more effectively.

Furthermore, because the combustion burner includes, as the coolingunits, the liquid fuel injecting hole arranged on the vane pressuresurface of the swirler vane, and a water injecting hole that is arrangedupstream of the liquid fuel injecting hole that is arranged on the vanepressure surface of the swirler vane to inject water to the vanepressure surface of the swirler vane, a water film can be formed on thevane pressure surface of the swirler vane to reduce the temperature ofthe vane pressure surface of the swirler vane. In this manner, formationof carbon deposit can be prevented.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic of a structure of a combustion burner according toa first embodiment of the present invention.

FIG. 2 is a perspective view of the combustion burner according to thefirst embodiment, injecting water while only the liquid fuel LF iscombusted.

FIG. 3 is a schematic of another structure of the combustion burneraccording to the first embodiment.

FIG. 4 is a schematic of a structure of a combustion burner according toa second embodiment of the present invention.

FIG. 5 is a schematic of a structure of a combustion burner according toa third embodiment of the present invention.

FIG. 6 is a schematic of a structure of a combustion burner according toa fourth embodiment of the present invention.

FIG. 7 is a schematic of a structure of a combustion burner according toa fifth embodiment of the present invention.

FIG. 8 is a schematic of an exemplary structure of a combustion burnerincluded in a combustor of a conventional gas turbine.

FIG. 9 is a schematic of an exemplary structure of another conventionalcombustion burner.

FIG. 10 is a perspective view of a combustion nozzle included in theconventional combustion burner.

EXPLANATIONS OF LETTERS OR NUMERALS

-   10A to 10E combustion burner-   11-1 to 11-3 multi-purpose injecting hole-   12 liquid fuel tank-   13 gas fuel tank-   14 water tank-   15A to 15C water film-   16A, 16B-1 to 16B-3 water injecting hole-   17 static mixer-   18A to 18E atomized mixed fuel-   21 water cooling circuit-   110 fuel nozzle-   111 air passage-   120 burner tube-   121 clearance-   130 swirler vane-   131 clearance setting rib-   132 a vane pressure surface-   132 b vane suction surface-   133A, 133B, 133C-1 to 133C-3 liquid fuel injecting holes-   200 pilot combustion burner-   A compressed air-   a swirling air flow-   W water-   GF gas fuel-   LF liquid fuel-   MF mixed fuel-   L11 liquid fuel supplying line

L21 to L23 gas fuel supplying lines

-   L31 to L33 water supplying lines-   V₁₁, V₂₁ to V₂₃, V₃₁ to V₃₃ valve

BEST MODE(S) FOR CARRYING OUT THE INVENTION

The present invention will now be explained in detail with reference tothe attached drawings. The embodiments disclosed herein are not intendedto limit the scope of the present invention in any way. Furthermore,elements disclosed in the embodiment include those that can be easilyimagined by those in the art, or those that are substantially identical.

First Embodiment

A combustion burner according to a first embodiment of the presentinvention will now be explained with reference to some of the attacheddrawings.

FIG. 1 is a schematic of a structure of the combustion burner accordingto the first embodiment of the present invention.

In FIG. 1, elements that are the same as those shown in FIGS. 8 to 10are given the same reference numerals, and redundant explanationsthereof are omitted.

As shown in FIG. 1, a combustion burner 10A according to the presentembodiment includes: the fuel nozzle 110; the burner tube 120surrounding the fuel nozzle 110 to form the air passage 111 between theburner tube 120 and the fuel nozzle 110; the swirler vanes (swirlervanes) 130 arranged in a plurality of positions in the circumferentialdirection on the external circumferential surface of the fuel nozzle110, each extending along the axial direction of the fuel nozzle 110,and gradually curving from upstream to downstream of an air that flowsthrough the air passage 111 so as to swirl the air flowing from theupstream to the downstream; the liquid fuel injecting hole 133A that isarranged on the fuel nozzle 110, and through which the liquid fuel LF isinjected to a surface of each of the swirler vanes 130; and a coolingunit that cools a part of the vane surface on which the liquid fuel LFhits.

The cooling unit according to the present embodiment is arranged on thevane pressure surface 132 a of the swirler vane 130. Upon combusting agas fuel GF (during gas firing), the gas fuel GF is injected; and uponcombusting liquid fuel LF (during oil firing), water W is injected tothe vane pressure surface 132 a of the swirler vane 130. In other words,the cooling unit includes multi-purpose injecting holes 11-1 to 11-3through which not only a gas fuel but also water is injected to cool thevane pressure surface 132 a while the water is injected (details thereofare to be described later).

The burner tube 120 is arranged along the same axis as the fuel nozzle110, surrounding the fuel nozzle 110. Therefore, the ring-like airpassage 111 is formed between the external circumferential surface ofthe fuel nozzle 110 and the inner circumferential surface of the burnertube 120. The compressed air A flows through the air passage 111 fromthe upstream (the left-hand side in FIG. 1) to the downstream of the airpassage 111 (the right-hand side in FIG. 1).

The swirler vanes 130 are arranged in a plurality of positions in thecircumferential direction of the fuel nozzle 110, extending along theaxial direction of the fuel nozzle 110. Each of the swirler vanes 130gives a swirling force to the compressed air A that flows through theair passage 111 to obtain a swirling air flow a. To achieve this goal,each of the swirler vanes 130 is gradually curved from the upstream tothe downstream (inclined in the circumferential direction) so that theswirler vane 130 can swirl the compressed air A.

In other words:

-   (1) each of the swirler vanes 130 is gradually curved from the    upstream to the downstream so that the swirler vane 130 can swirl    the compressed air A;-   (2) the degree of the curve in the axial direction (the longitudinal    direction of the fuel nozzle 110) is increased from The upstream to    the downstream; and-   (3) in the rear edge of the swirler vane 130, the degree of the    curve in the radial direction (the radial (radiating) direction of    the fuel nozzle 110) is increased toward the external    circumferential direction than that toward internal circumferential    direction.

The clearance (gap) 121 is kept between the end surface (tip) of theexternal circumference of each of the swirler vanes 130 and the innercircumferential surface of the burner tube 120. A positive pressure isapplied to the vane pressure surface 132 a (see FIG. 2) of the swirlervane 130, and a negative pressure is applied onto a vane suction surface132 b (see FIG. 2) of the swirler vane 130; that is, there is a pressuredifference between the pressure on the vane suction surface 132 b andthe pressure on the vane pressure surface 132 a. Therefore, a leakingair flow, flowing around the vane pressure surface 132 a to the vanesuction surface 132 b, is generated through the clearance 121. Thisleaking flow interferes with the compressed air A flowing through theair passage 111 along the axial direction, to generate a vortical airflow. By way of such a vortical air flow, the air is effectively mixedwith the fuel that is injected to the vane pressure surface 132 athrough the liquid fuel injecting holes 133A, making the fuel vaporizedand atomized, and making the gas fuel GF uniform.

The clearance setting rib 131 is fixed on a front-side end surface (tip)of the external circumference of each of the swirler vanes 130. Theheight (radial length) of each of the clearance setting ribs 131 is setso that, when the fuel nozzle 110 having the swirler vanes 130 isassembled to the burner tube 120, each of the clearance setting ribs 131is brought in a close contact with the internal circumferential surfaceof the burner tube 120.

Therefore, the length (radial length) of each of the clearances 121,formed between each of the swirler vanes 130 and the burner tube 120,will be equal. Furthermore, the fuel nozzle 110 having the swirler vanes130 can easily be assembled into the burner tube 120.

The fuel nozzle 110 is formed with a plurality of the liquid fuelinjecting holes 133A for injecting and spraying a fuel onto the vanepressure surface 132 a. In the combustion burner 10A according to thepresent embodiment, the liquid fuel injecting holes 133A are arranged onthe fuel nozzle 110. Each of the liquid fuel injecting holes 133A isarranged at a position near the vane pressure surface 132 a of each ofthe swirler vanes 130, on the external circumference of the fuel nozzle110.

A liquid fuel supplying line L11 is formed in the fuel nozzle 110. Theliquid fuel LF is supplied from a liquid fuel tank 12 to each of theliquid fuel injecting holes 133A via the liquid fuel supplying line L11.At this time, the amount of the supplied liquid fuel LF is adjusted witha valve V11.

In the present embodiment, the position and the orientation of each ofthe liquid fuel injecting holes 133A are set so that the liquid fuel LFinjected through each of the liquid fuel injecting holes 133A is sprayedto the vane pressure surface 132 a of each of the swirler vanes 130.Because the degree of the curve of the vane pressure surface 132 a isincreased toward the external circumferential direction from theinternal circumferential direction (toward the radiating direction), theliquid fuel LF can be sprayed to the vane pressure surface 132 a tospread the liquid fuel LF into a thin film on the vane pressure surface132 a, simply by injecting the liquid fuel LF through each of the liquidfuel injecting holes 133A in the radial direction (radiating direction).

The liquid fuel LF, spread into a thin film on the vane pressure surface132 a, is brought in contact with the compressed air A (or the swirlingair flow a) that is an air flow at a high temperature and a high speedto become vaporized. In other words, the liquid fuel LF, spread into athin film on the vane pressure surface 132 a, is peeled off andvaporized by way of a shearing force produced by a steep airflowboundary layer velocity gradient on the vane pressure surface 132 a.

The liquid fuel LF that is spread into a thin film is vaporized asmentioned above; however, the liquid fuel LF that is not completelyvaporized spreads out on the vane pressure surface 132 a and moves fromthe front end toward the rear end of the vane. The liquid fuel LF thathas spread into a thin film and reached the rear end of the vane ispeeled off of the rear end and becomes atomized by way of the high-speedcompressed air A (the swirling air flow a). At this time, because thethickness of the thin liquid fuel LF is extremely small, the diameter ofthe atomized liquid fuel LF will also be extremely small. Because theliquid fuel LF, atomized to have extremely small diameter, is mixed withthe swirling air flow a (including the vortical air flow), vaporizationthereof is further promoted.

In this manner, the liquid fuel LF is injected to the vane pressuresurface 132 a to promote atomization, vaporization, and gasification ofthe liquid fuel LF. The liquid fuel LF atomized to have extremely smallparticle diameter and vaporized is mixed with air and combusted.Therefore, good combustion can be achieved.

Furthermore, in the combustion burner 10A according to the presentembodiment, the multi-purpose injecting holes 11-1 to 11-3 are arrangedon the vane pressure surface 132 a of the swirler vane 130. Themulti-purpose injecting holes 11-1 to 11-3 inject the gas fuel GF duringthe gas firing, and inject the water W to the vane pressure surface 132a of the swirler vane 130 while the liquid fuel LF is being combusted(during oil firing).

During the gas firing, the gas fuel GF is supplied from a gas fuel tank13 to the multi-purpose injecting holes 11-1 to 11-3 via gas fuelsupplying lines L21 to L23. The supplied gas fuel GF is injected throughthe multi-purpose injecting holes 11-1 to 11-3 to the vane pressuresurface 132 a of the swirler vane 130. The amount of the supplied gasfuel GF is controlled by valves V₂₁ to V₂₃.

Therefore, during the gas firing, the gas fuel GF can be injectedthrough the injecting holes 11-1 to 11-3. At the same time, the liquidfuel LF can be injected through the liquid fuel injecting holes 133A tothe vane pressure surface 132 a to obtain a dual firing gas turbine thatcombusts the gas fuel GF and the liquid fuel LF simultaneously.

When only the liquid fuel LF is combusted, the water W is supplied fromthe a water tank 14 via water supplying lines L31 to L33, and thesupplied water W is injected to the vane pressure surface 132 a of theswirler vane 130 through the multi-purpose injecting holes 11-1 to 11-3.The amount of the supplied water W is adjusted with valves V₃₁ to V₃₃.

FIG. 2 is a perspective view of the combustion burner according to thefirst embodiment, injecting water while only the liquid fuel LF iscombusted. As shown in FIG. 2, while the liquid fuel LF is combusted,the water W, supplied from the water tank 14 via the water supplyinglines L31 to L33, forms a water film 15A on the surface of the vanepressure surface 132 a of each of the swirler vanes 130.

The water W, injected through the multi-purpose injecting holes 11-1 to11-3 and formed into the water film 15A, is mixed with the liquid fuelLF injected through each of the liquid fuel injecting holes 133A, andatomized at the tip of the vanes, and an atomized mixed fuel 18A fliesapart toward downstream of the air passage 111.

In this manner, during the oil firing, because the water W is suppliedthrough the multi-purpose injecting holes 11-1 to 11-3 to form the waterfilm 15A on the vane surface, it is possible to cool the part of thevane pressure surface 132 a on which the liquid fuel LF hits. In thismanner, formation of carbon deposit can be prevented.

Furthermore, because the multi-purpose injecting holes 11-1 to 11-3 areused as water supply holes for supplying the water W, fluid channelsprovided in the fuel nozzle 110 can be prevented from being complex inshape.

Further more, by simply applying the gas fuel injecting holes to anexisting combustion burner with an addition of the water supply lines,the water W can be injected to the vane pressure surface 132 a of eachof the swirler vanes 130 and the formation of the carbon deposit can beprevented.

Furthermore, because the combustion temperature can be reduced by way ofthe water W supplied through the multi-purpose injecting holes 11-1 to11-3, NO_(x) in the combustion field can be reduced.

In the combustion burner 10A according to the present embodiment, theliquid fuel LF and the water W are introduced after a pilot nozzle, notshown, raises the load and then the pilot ratio is reduced. This isbecause, if the water W is introduced while the liquid fuel LF isinjected, the amount of the water W will become relatively greater.Therefore, the water W needs to be introduced after the load is raisedto a certain level.

In the combustion burner 10A according to the present embodiment, thewater W is supplied intermittently after the pilot nozzle, not shown,raises the load; however, the present invention is not limited thereto,and the water W may be continuously supplied and mixed with the liquidfuel LF even before the pilot nozzle raises the load.

Furthermore, in the combustion burner 10A according to the presentembodiment, the gas fuel supplying lines L21 to L23 for supplying thegas fuel GF from the gas fuel tank 13 is provided separately from thewater supplying lines L31 to L33 for supplying the water W from thewater tank 14, to inject either the gas fuel GF or the water W throughthe multi-purpose injecting holes 11-1 to 11-3; however, the presentinvention is not limited thereto, and the gas fuel supplying lines L21to L23 and the water supplying lines L31 to L33 may be connected inbetween, as shown in FIG. 3, to supply either the gas fuel GF or thewater W through the multi-purpose injecting holes 11-1 to 11-3.

Furthermore, in the combustion burner 10A according to the presentembodiment, the liquid fuel LF is injected to the vane pressure surface132 a of the swirler vane 130 through the liquid fuel injecting holes133A; however, the present invention is not limited thereto, and theliquid fuel LF may be injected to the vane suction surface 132 b of theswirler vane 130 through the liquid fuel injecting holes 133A.Alternatively, the liquid fuel LF may be injected to both of the vanepressure surface 132 a and the vane suction surface 132 b of the swirlervane 130, through the liquid fuel injecting holes 133A.

As described above, the combustion burner 10A according to the presentembodiment includes the multi-purpose injecting holes 11-1 to 11-3 thatare arranged on the vane pressure surface 132 a of the swirler vane 130and are commonly used for injecting the water and for injecting the gasfuel, to inject the water W to the vane pressure surface 132 a of theswirler vanes 130 during a combustion in which only the liquid fuel LFis used, and to inject the gas fuel GF during the gas firing operation.Therefore, the water film 15A is formed on the vane pressure surface 132a of the swirler vane 130 to cool the part of the vane pressure surface132 a on which the liquid fuel LF hits. In this manner, it is possibleto suppress heating of the part of the vane pressure surface 132 a onwhich the liquid fuel LF hits. Therefore, the combustion temperature canbe reduced, to prevent a formation of carbon deposit, as well as toreduce NO_(x) in the combustion field.

Second Embodiment

A combustion burner according to a second embodiment of the presentinvention will now be explained with reference to FIG. 4.

The combustion burner according to the present embodiment has almost thesame structure as that of the combustion burner 10A according to thefirst embodiment shown in FIG. 1; therefore, the same reference numeralsare given to the elements that are same as those in the combustionburner 10A shown in FIG. 1, and redundant explanations thereof areomitted.

In the present embodiment, only the combustion nozzle 110 and theswirler vanes 130 are described and the other elements are omitted. Thesame can be said in the remaining embodiments.

FIG. 4 is a schematic of a structure of the combustion burner accordingto the second embodiment of the present invention.

As shown in FIG. 4, in a combustion burner 10B according to the presentembodiment, the multi-purpose injecting holes 11-1 to 11-3, which arearranged on the vane pressure surface 132 a of the swirler vane 130 inthe combustion burner 10A according to the first embodiment, are nowarranged on the fuel nozzle 110 too, each in line with each of theliquid fuel injecting holes 133A along the axial direction.

In other words, the combustion burner 10B according to the presentembodiment includes, as the cooling unit, independent water injectingholes 16A each of which is arranged on the fuel nozzle 110 too in linewith each of the liquid fuel injecting holes 133A at a position upstreamof each of the liquid fuel injecting holes 133A along the axialdirection, and from which the water W is injected to the vane pressuresurface 132 a of each of the swirler vanes 130.

FIG. 4 is a schematic indicating where the water is injected.

Each of the water injecting holes 16A is arranged on the fuel nozzle 110at a position upstream of each of the liquid fuel injecting holes 133Ain line therewith to inject the water W to the vane pressure surface 132a of the swirler vanes 130. The water W is injected through the waterinjecting holes 16A to the part of the vane pressure surface 132 a ofthe swirler vane 130 on which the liquid fuel LF hits, to form a waterfilm 15B on the vane pressure surface 132 a of the swirler vane 130. Thewater W injected through the water injecting holes 16A and is formedinto the water film 15B is mixed with the liquid fuel LF injectedthrough each of the liquid fuel injecting holes 133A, and is atomized atthe tip of the swirler vane 130. An atomized mixed fuel 18B flies apartdownstream of the air passage 111 shown in FIG. 1.

In this manner, the water W is supplied through the water injectingholes 16A to form the water film 15B on the vane pressure surface 132 a.The water film 15B cools the part of the vane pressure surface 132 a onwhich the liquid fuel LF hits to reduce the temperature on the vanesurface. Therefore, the combustion temperature can be reduced, toprevent formation of carbon deposit.

Third Embodiment

A combustion burner according to a third embodiment of the presentinvention will now be explained with reference to FIG. 5.

The combustion burner according to the present embodiment has almost thesame structure as that of as the combustion burner 10A according to thefirst embodiment shown in FIG. 1; therefore, the same reference numeralsare given to the elements that are same as those in the combustionburner 10A shown in FIG. 1, and redundant explanations thereof areomitted.

In the third embodiment, only the combustion nozzle 110 and the swirlervanes 130 are described, and the other elements are omitted.

FIG. 5 is a schematic of a structure of the combustion burner accordingto the third embodiment of the present invention.

As shown in FIG. 5, in a combustion burner 10C according to the presentembodiment, the multi-purpose injecting holes 11-1 to 11-3, which arearranged on the vane pressure surface 132 a of the swirler vanes 130 inthe combustion burner 10A according to the first embodiment shown inFIG. 1, and the liquid fuel injecting holes 133A are now combined.

In other words, the combustion burner 10C according to the presentembodiment injects a mixed fuel MF prepared by mixing the water W andthe liquid fuel LF evenly to the vane pressure surface 132 a of each ofthe swirler vanes 130 through liquid fuel injecting holes 133B, as thecooling unit.

In the combustion burner 10C according to the present embodiment, thefuel nozzle 110 includes a static mixer 17 for mixing the water W andthe liquid fuel LF homogeneously. The mixed fuel MF prepared by mixingthe water W and the liquid fuel LF evenly in the static mixer 17 isgushed out of the liquid fuel injecting holes 133B.

In a conventional combustion burner, when the water W and the liquidfuel LF are mixed using the static mixer 17, for example, the water Wand the liquid fuel LF are mixed at a position further upstream in thefuel nozzle 110. Therefore, there are situations where the water W andthe liquid fuel LF become separated while passing through the fuelnozzle 110.

On the contrary, in the combustion burner 10C according to the presentembodiment, the static mixer 17 mixes the water W and the liquid fuel LFat a position immediately near the liquid fuel injecting holes 133B, themixed fuel MF can be gushed out of the liquid fuel injecting hole 133Bwithout permitting the water W and the liquid fuel LF to becomeseparated. The mixed fuel MF injected through each of the liquid fuelinjecting holes 133B is atomized at the tip of each of the vanes, and anatomized mixed fuel 18C flies apart toward downstream of the air passage111 such as the one shown in FIG. 1.

The water W is added to the liquid fuel LF in a liquid fuel supplyingline L31 that is similar to the one shown in FIG. 1. Because the boilingtemperature of the water W is lower than that of the liquid fuel LF suchas oil, the water W becomes vaporized first to reduce the combustiontemperature to deprive temperature from the surface of the swirler vanes130. Therefore, formation of carbon deposit can be prevented.

Furthermore, in the combustion burner 10C according to the presentembodiment, it is not necessary to provide the multi-purpose injectingholes 11-1 to 11-3 such as those provided on the combustion burner 10Aaccording to the first embodiment shown in FIG. 1, and the water W isonly gushed out of the liquid fuel injecting holes 133B. Therefore, itis possible to reduce the number of injecting holes arranged on the fuelnozzle 110 or the swirler vanes 130.

In the combustion burner 10C according to the present embodiment, thestatic mixer 17 mixes the water W and the liquid fuel LF evenly;however, the present invention is not limited thereto, and anything canbe used as long as the water W and the liquid fuel LF can be mixedevenly.

Fourth Embodiment

A combustion burner according to a fourth embodiment of the presentinvention will now be explained with reference to FIG. 6.

The combustion burner according to the present embodiment has almost thesame structure as that of the combustion burner 10A according to thefirst embodiment shown in FIG. 1; therefore, the same reference numeralsare given to the elements that are same as those in the combustionburner 10A shown in FIG. 1, and redundant explanations thereof areomitted.

In the present embodiment, only the combustion nozzle 110 and theswirler vanes 130 are described, and the other elements are omitted.

FIG. 6 is a schematic of a structure of the combustion burner accordingto the fourth embodiment of the present invention.

As shown in FIG. 6, in the combustion burner 10D according to thepresent embodiment, the liquid fuel injecting holes 133A, which arearranged on the fuel nozzle 110 in the combustion burner 10A accordingto the first embodiment shown in FIG. 1, are now arranged on the vanepressure surface 132 a of the swirler vanes 130.

In other words, the combustion burner 10D according to the presentembodiment includes, as the cooling unit, liquid fuel injecting holes133C-1 to 133C-3 that are arranged on the vane pressure surface 132 a ofeach of the swirler vanes 130, and water injecting holes 168-1 to 16B-3that are arranged upstream of the liquid fuel injecting holes 133C-1 to133C-3 (the left-hand side in FIG. 6) on the vane pressure surface 132 aof the swirler vane 130 for injecting the water W to the vane pressuresurface 132 a of the swirler vane 130.

FIG. 6 is a schematic indicating where the water is injected.

The water W is gushed out of the water injecting holes 16B-1 to 16B-3,arranged upstream on the vane pressure surface 132 a of the swirler vane130, to the vane pressure surface 132 a of the swirler vane 130 to forma water film 15C on the surface of the vane pressure surface 132 a ofthe swirler vane 130, to reduce the temperature at the vane surface ofthe swirler vane 130. The liquid fuel LF is injected through the liquidfuel injecting holes 133C-1 to 133C-3 arranged downstream of the waterinjecting holes 168-1 to 168-3. The water W, injected through each ofthe water injecting holes 168-1 to 16B-3 and is formed into the waterfilm 15C, and the liquid fuel LF, injected through each of the liquidfuel injecting holes 133C-1 to 133C-3, are mixed and become atomized atthe tip of the vane. An atomized mixed fuel 18D flies apart toward thedownstream of the air passage 111, such as the one shown in FIG. 1.

As described above, the water W is supplied from the water injectingholes 16B-1 to 16B-3, arranged upstream of the liquid fuel injectingholes 133C-1 to 1330-3, to form the water film 15C on the surface of theswirler vane 130. In this manner, the temperature on the vane pressuresurface 132 a of the swirler vane 130 can be reduced. Therefore,formation of carbon deposit can be prevented.

Furthermore, the concentration distribution can be finely adjusted byinjecting the liquid fuel LF from a surface of the swirler vane 130where carbon deposit is less likely to occur.

Fifth Embodiment

A combustion burner according to a fifth embodiment of the presentinvention will now be explained with reference to FIG. 7.

The combustion burner according to the present embodiment has almost thesame structure as that of the combustion burner 10A according to thefirst embodiment shown in FIG. 1; therefore, the same reference numeralsare given to the elements that are same as those in the combustionburner 10A shown in FIG. 1, and redundant explanations thereof areomitted.

In the present embodiment, only the combustion nozzle 110 and theswirler vanes 130 are described, and the other elements are omitted.

FIG. 7 is a schematic of a structure of the combustion burner accordingto the fifth embodiment of the present invention.

As shown in FIG. 7, in a combustion burner 10E according to the presentembodiment, a water cooling circuit 21 is formed inside the swirler vane130, instead of the multi-purpose injecting holes 11-1 to 11-3 arrangedon the vane pressure surface 132 a of the swirler vane 130 included inthe combustion burner 10A according to the first embodiment shown inFIG. 1.

In other words, the combustion burner 10E according to the presentembodiment includes, as the cooling unit, a water cooling circuit formedinside the swirler vane.

FIG. 7 is a schematic that indicates the water cooling circuit injectingwater.

The water cooling circuit 21 is formed inside the swirler vane 130, andthe inside of the swirler vane 130 is cooled by way of the water Wflowing inside the swirler vane 130. The water W supplied to the watercooling circuit 21 is supplied via the water supplying line L31 such asthe one shown in FIG. 1. The water W after cooling and being used in thewater cooling circuit 21 is sprayed to the air passage 111 from the tipof the swirler vane 130 to become atomized.

The liquid fuel LF injected through the liquid fuel injecting holes 133Aarranged on the fuel nozzle 110 becomes atomized. The atomized water andthe atomized liquid fuel LF injected through each of the liquid fuelinjecting holes 133A are mixed and atomized at the tip of the vane, andan atomized mixed fuel 18E flies apart toward the downstream of the airpassage 111 such as the one shown in FIG. 1.

Therefore, by using the combustion burner 10E according to the fifthembodiment including the water cooling circuit 21 arranged inside theswirler vane 130 to cool the swirler vane 130 from its inside, thetemperature on the surface of the swirler vane 130 can be reduced,thereby cooling the part of the vane pressure surface 132 a on which theliquid fuel LF hits, thus preventing the swirler vanes 130 from beingheated up. In this manner, the combustion temperature can be reduced.Therefore, formation of carbon deposit can be prevented moreeffectively.

Furthermore, the mixing of the water W, which is used in the watercooling circuit 21 and flies apart at the tip of the vane to becomeatomized, and the liquid fuel LF, which is injected through the liquidfuel injecting holes 133A to become atomized, can be promoted by way ofswirls of the flows in downstream area.

Industrial Applicability

As described above, the combustion burner according to the presentinvention can cool the part of the swirler vane surface on which theliquid fuel hits to suppress that part from being heated up. Therefore,the combustion burner according to the present invention is suited to beused as a combustion burner in a gas burner for suppressing carbondeposit formation.

The invention claimed is:
 1. A combustion burner comprising: a fuelnozzle; a burner tube that surrounds the fuel nozzle to form an airpassage between the burner tube and the fuel nozzle; a plurality ofswirler vanes being arranged in a plurality of positions in acircumferential direction on an external circumferential surface of thefuel nozzle, each of which extends along an axial direction of the fuelnozzle, and gradually curves from upstream to downstream so as to swirlair flowing in the air passage from the upstream to the downstream; aliquid fuel injecting hole that is formed on the fuel nozzle, and fromwhich a liquid fuel is injected to a vane pressure surface of each ofthe swirler vanes; and a cooling unit that cools a part of the vanepressure surface on which the liquid fuel hits, wherein the cooling unitprovided on the fuel nozzle includes a water injecting hole that isarranged upstream of the liquid fuel injecting hole provided on the fuelnozzle, and in line therewith, and from which water is injected to thevane pressure surface of the swirler vane.